Diisocyanate polyaddition products dispersed in polyethers or polyesters are already known. According to German Auslegeschrift No. 1,168,075, diisocyanates are reacted with difunctional primary alcohols in a polyether or polyester having a molecular weight 500 to 3000 used as dispersing medium, said polyether or polyester having at least two exclusively secondary, hydroxyl groups in the molecule. According to German Auslegeschrift No. 1,260,142, compounds containing isocyanate groups and amino groups are subjected to polyaddition in situ in a polypropylene glycol ether used as dispersing medium. An improvement to the above mentioned processes is described in German Offenlegungsschrift No. 2,513,815, according to which the in situ polyaddition reaction is carried out continuously in a through-flow mixer. The resulting dispersion of polyurethanes, polyureas or polyhydrazodicarbonamides in polyvalent, higher molecular weight compounds containing hydroxyl groups can be used as modified polyol components containing fillers for the production of polyurethane resins.
According to two earlier proposals by the present Applicants in German Offenlegungsschriften Nos. 2,550,796 and 2,550,797, stable dispersions of polyisocyanate polyaddition products in dispersing agents consisting of hydroxyl containing compounds are obtained by in situ reaction of polyisocyanates with amino functional compounds which may contain ionic groups in the dispersing medium, the reaction being carried out in the presence of water. Both of these earlier applications, however, are also confined to the preparation and use of dispersions.